The melanotic polyp syndrome consists of three parts: 1) gastrointestinal melanotic polyps; 2) autosomal dominant inheritance; 3) melanosis of the skin mucosa. The melanotic polyp syndrome is also known as cutaneous mucosal melanotic polyp syndrome. It has an equal incidence in men and women, and is mostly seen in children and adolescents. The clinical features are excessive melanosis on the lips and oral mucosa, and sometimes melanosis on the skin of the fingers and toes. Polyps are most commonly found in the small intestine, especially the jejunum, followed by the stomach and large intestine. Most people have multiple polyps, but a few may also have one polyp. The polyps range from a few millimeters to 5 cm in diameter, small ones without a tip or large ones with a tip, and have the appearance of a large intestinal adenoma. After exploration and research, dark spot polyps can be diagnosed by ultrasound. It is superior to other imaging diagnostics.